When it comes to phones and tablets, the application store is your gateway to entertainment. There are millions of games, music players, social media platforms, and other useful tools in these stores. And many of the popular ones are completely free!

Apps that aren't free normally cost a few bucks. But sometimes you can get them for free from the App Store (iOS devices) if it's being featured as the free app of the week. The Apple App store has been doing these weekly features since 2012 and now the Google Play store (Android devices) is finally following suit.

This app is a game that was inspired by an episode of the Cartoon Network show "Adventure Time." "Summon creatures and cast spells to battle your way to victory," said the app's description. It looks like a game where you strategically use special cards to challenge characters from the show.

This isn't the first time that Google has featured an app and offered it for free. In 2015, people were able to download a PBS Kids app for free from the family section of the store. Also, people have been able to download free Android apps through Amazon Underground, a paid service that offers free downloads.

It's not clear if this promotion is here to stay. For right now, Google is considering it a pilot program that will run for four weeks. Plus, "Free App of the Week" is only available for people in the U.S.